Material handling apparatus

ABSTRACT

A material handling vehicle having a bucket which is movable between dig, carry and dump orientations is provided with an improved apparatus for controlling operation of a motor which moves the bucket between these orientations. This improved apparatus includes a magnet which is moved to a reference position adjacent to a detector upon movement of the bucket from the dump orientation to the dig orientation. When the magnet is in the reference position, its magnetic field activates the detector to provide an output signal and interrupt operation of the bucket positioning motor. A pole shading member of a magnetizable material is associated with the magnet to diffuse its field and prevent double pulsing and premature activation of the detector during movement of the bucket toward the dig orientation. A second magnet is provided to activate the detector and interrupt operation of the bucket positioning motor when the bucket is moved to the carry orientation. The two magnets are disposed in a coaxial relationship in a tube having a pointer which provides a visual indication of the position of the bucket. In addition, a second detector is activated by a third magnet to interrupt operation of a bucket elevating motor when the bucket has been moved from a lowered position to a raised position.

United States Patent [1 1 Brundige et al.

1 June 3, 1975 MATERIAL HANDLING APPARATUS [75] Inventors: Clayton L. Brundige, Rochester;

William H. Bechman, Williamsville, both of NY.

[73] Assignt e: Eaton Corp., Cleveland, Ohio [22] Filed: Sept. 28, 1973 [21] Appl. No.: 401,685

[52] [1.8. CI. 214/762; 91/459; 335/205 [51] Int. Cl E02f 3/84 [58] Field of Search 214/762, 763, 764', 91/355,

Primary ExaminerRobert .1. Spar Assistant Examiner-Ross Weaver Attorney, Agent, or FirmTeagno & Toddy 5 7 ABSTRACT A material handling vehicle having a bucket which is movable between dig, carry and dump orientations is provided with an improved apparatus for controlling operation of a motor which moves the bucket between these orientations. This improved apparatus includes a magnet which is moved to a reference position adjacent to a detector upon movement of the bucket from the dump orientation to the dig orientation. When the magnet is in the reference position, its magnetic field activates the detector to provide an output signal and interrupt operation of the bucket positioning motor. A pole shading member of a magnetizable material is associated with the magnet to diffuse its field and prevent double pulsing and premature activation of the detector during movement of the bucket toward the dig orientation. A second magnet is provided to antivate the detector and interrupt operation of the bucket positioning motor when the bucket is moved to the carry orientation. The two magnets are disposed in a coaxial relationship in a tube having a pointer which provides a visual indication of the position of the bucket. In addition, a second detector is activated by a third magnet to interrupt operation of a bucket elevating motor when the bucket has been moved from a lowered position to a raised position.

14 Claims, 9 Drawing Figures PNE EDJUH m5 SHEET FIG. 9

MATERIAL HANDLING APPARATUS BACKGROUND OF THE INVENTION This invention relates generally to a material handling apparatus and more specifically to an improved arrangement for detecting when a load supporting member, such as a bucket, is in a predetermined position and attitude.

A known material handling vehicle has been provided with controls to interrupt operation of a bucket positioning motor when the bucket is in a load or dig orientation. Thus, the material handling vehicle dis closed in U.S. Pat. No. 3,519,155 utilizes a magnet to actuate a proximity switch when the bucket has been moved from a dump orientation to a dig or load orientation. Upon actuation of the proximity switch, a detent assembly is released to interrupt operation of a bucket positioning motor.

During material handling operations, a loaded bucket is frequently moved upwardly to a raised position before being dumped. Operation of a bucket elevating motor has previously been interrupted when the bucket has been moved to the raised position by mechanical actuation of a detector switch as disclosed in U.S. Pat. No. 3,642,159.

SUMMARY OF THE PRESENT INVENTION The present invention provides a new and improved apparatus for controlling movement of a material supporting member. Although the improved apparatus could be used with many different types of material supporting members, including a load support platform or shuttle device, in one specific preferred embodiment of the invention the apparatus is utilized in association with the bucket of a material handling vehicle. When the bucket has been moved from a dump orientation to a dig or loading orientation, a magnet activates a detector which provides an output signal to interrupt operation of a bucket positioning motor. To prevent premature activation of the detector as the bucket moves toward the dig orientation, a pole shading member of magnetizable material is disposed adjacent to a leading end of the magnet. The pole shading member diffuses or disperses the portion of the magnetic field associated with the leading end of the magnet so that the detector is not activated until the trailing end of the magnet is in close proximity with the detector.

After the bucket has been loaded in a known manner. the bucket positioning motor is operated to move the bucket from the dig orientation to an upright carry orientation. When the bucket reaches the carry orientation, a second magnet again activates the detector to provide an output signal to interrupt operation of the bucket positioning motor. The two magnets are advantageously disposed within a tubular member formed of a nonmagnetic material. The positions of the magnets can be adjusted axially along the tubular member to provide precise adjustment of the magnets relative to the detector.

Once the bucket has been loaded and moved to the carry orientation, it is contemplated that the bucket may be moved from a lowered position to a raised position prior to being dumped. In accordance with known practices, this is accomplished by pivoting a bucket support boom upwardly with a bucket elevating motor. In accordance with a feature of the present invention, a magnet is moved with the bucket support boom to activate a second detector when the bucket has been moved to the raised position. An output signal from the second detector is effective to interrupt operation of the bucket elevating motor. To provide for a precise adjustment of the raised position to which the bucket is moved, the position of the magnet can be adjusted relative to the bucket support boom.

Accordingly, it is an object of this invention to provide a new and improved material handling apparatus which includes a load carrying member and a detector which is activated under the influence of a magnetic field emanating from a magnet to provide an output signal upon movement of the load carrying member to a predetermined position.

Another object of this invention is to provide a new and improved material handling apparatus which includes a material support, such as a bucket or other device, which is moved to a predetermined position by a motor, a detector which is activated under the influence ofa magnetic field emanating from a magnet upon movement of the material support to the predetermined position, and a pole shading member for diffusing the portion of the magnetic field associated with a leading end of the magnet to prevent premature activation of the detector as the magnet is moved toward the detector.

Another object of this invention is to provide a new and improved material handling apparatus which includes a bucket which is movable from a dig or loading orientation to either a dump or carry orientation under the influence of a bucket positioning motor and wherein a first magnet is provided to activate a detector upon movement of a bucket to a loading orientation and a second magnet is provided to activate the detector upon movement of the bucket to the carry orientation.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and features of the present invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a schmatic illustration ofa material handling vehicle having a bucket which is illustrated in solid lines in a dig or loading orientation and in dashed lines in a carry orientation;

FIG. 2 is a schematic illustration of the material handling vehicle of FIG. 1 with the bucket in a raised position, the bucket being shown in solid lines in a carry orientation and in dashed lines in a dump orientation;

FIG. 3 is a schematic illustration of a control apparatus for effecting operation of a bucket positioning motor to move the bucket between the dig, carry, and dump orientations;

FIG. 4 is an enlarged fragmentary illustration depicting the relationship between the bucket positioning motor and an actuator rod assembly for effecting activation of a detector upon movement of the bucket to either the dig or carry orientations;

FIG. 5 is an enlarged fragmentary sectional view, taken along the line 5-5 of FIG. 4, illustrating the construction of the actuator rod assembly;

FIG. 6 is a sectional view, taken generally along the line 6-6 of FIG. 4, illustrating the relationship between the bucket positioning motor, detector, and actuator rod assembly;

FIG. 7 is a schematic illustration depicting the relationship between a magnet and a pole shading member in the actuator rod assembly of FIG.

FIG 8 is a schematic illustration depicting a relationship between a magnet mounted on a bucket support boom and a detector for providing an output signal to deactivate a bucket elevating motor upon movement of the bucket to the raised position of FIG. 2; and

FIG. 9 is a fragmentary view taken generally along the line 9-9 of FIG. 8 further illustrating the relationship between the magnet and detector.

DESCRIPTION OF ONE SPECIFIC PREFERRED EMBODIMENT OF THE INVENTION A material handling vehicle 10 (FIG. I) is provided with a movable boom 12 which supports a bucket 14. When the bucket 14 has been filled during operation of the vehicle 10 in a known manner, a bucket positioning motor 16 is activated to operate a linkage l8 and pivot the bucket 14 from the load or dig orientation illustrated in solid lines in FIG. 1 to the carry orientation illustrated in dashed lines in FIG. 1. Once the loaded bucket 14 has been moved to the carry orientation, a bucket elevating motor 22 is activated to swing a boom 12 upwardly to move the bucket 14 to the raised position of FIG. 2. After the vehicle 10 has been driven to an unloading location, the bucket positioning motor 16 is again operated to pivot the bucket 14 from the upright carry orientation shown in solid lines in FIG. 2 to the dump orientation shown in dashed lines in FIG. 2.

A control assembly 28 (FIG. 3) is connected with the bucket positioning motor 16 by hydraulic lines 30 and 32. When an operator or control lever 36 is in the neutral position illustrated in FIG. 3. a motor control valve 38 blocks fluid flow to and from the bucket positioning motor 16. When the bucket 14 is to be moved from the dig orientation to the carry orientation, the lever 36 is pivoted in a counterclockwise direction (as viewed in FIG. 3) to actuate the motor control valve 38 to port fluid under pressure from a pump 40 to the motor 16 through circuit 32 and to connect the conduit 30 with a reservoir or drain tank 42. The fluid pressure in the conduit 32 is conducted to the rod end of the motor 16 to contract the motor and pivot the bucket 14 to the upright carry orientation. Similarly, when the bucket 14 is to be moved to the dump orientation, the actuator lever 36 is moved (in a clockwise direction as viewed in FIG. 3) to actuate the motor control valve 38 to port fluid under pressure to the conduit 30 and the head end of the motor 16. This extends the motor 16 to pivot the bucket 14 from the upright carry orientation to the dump orientation.

A detent assembly 46 is provided to hold the control lever 36 and motor control valve 38 in an actuated condition against the influence ofa biasing spring 48 (FIG. 3) which urges the motor control valve 38 to a neutral or unactuated condition blocking fluid flow to and from the motor 16. When the control lever 36 is pivoted in a counterclockwise direction to operate the motor control valve 38 to port fluid to the rod end of the motor 16, a detent roller 52 is pressed against a notch 54 under the influence of a detent biasing spring 56. When the roller 52 engages the notch 54, the detent assembly 46 holds the control lever 36 and motor control valve 38 in an actuated position porting fluid to the rod end of the motor 16. Similarly, when the lever 36 is moved in a clockwise direction from a neutral position. the detent roller 52 moves into engagement with a second notch 58 to retain the lever 36 and motor control valve 38 in an actuated condition in which fluid under pressure from the pump I4 is ported to the head end of the motor 16.

When the motor 16 has been operated to an extent sufficient to move the bucket I4 to either the carry or dig orientation. an improved actuator rod assembly 62 activates a detector 64. Upon being activated, the detector 64 provides an output signal which is transmitted over a lead 66 to a solenoid 68 connected with a valve 70. Upon energization of the solenoid 68, the valve 70 connects a piston and cylinder assembly 74 with the pump 40 through a conduit 76 as shown in FIG. 3. Fluid from the pump 40 causes the piston and cylinder assembly 74 to be extended to release the detent assembly 46 by pivoting an arm 78 in a counterclockwise direction (as viewed in FIG. 3) about a connection 80. This moves the roller 52 out of engagement with a notch 54 or 58 to release the control lever 36 for movement to the neutral position under the influence of the biasing spring 48. Although it is contemplated that many different types of motor control valves 38 and detent assemblies 46 could be utilized, the motor control valve 38 and detent assembly 46 are constructed in the manner disclosed in US. Pat. No. 3.5l9,l55. There fore, their construction and mode of operation will not be further described herein in order to avoid prolixity of description.

In accordance with the present invention. an improved actuator rod assembly 62 is provided to activate the detector 64 upon movement of the bucket 14 from the dump orientation (shown in dashed lines in FIG. 2) to the dig orientation (shown in solid lines in FIG. I). The actuator rod assembly 62 is also effective to activate the detector 64 upon movement of the bucket 14 from the dig orientation to the carry orientation (shown in dashed lines in FIG. 1). Of course, activation of the detector 64 effects a releasing of the detent assembly 46 and operation of the motor control valve 38 to neutral to thereby interrupt operation of the motor 16.

The actuator rod assembly 62 includes a cylindrical aluminum tube 84 (FIG. 4) which is connected at its outer end with the rod 88 of the bucket positioning motor 16 by a connector 92. The detector 64 is connected to a support bracket 96 (FIGS. 4 and 6) which is fixedly connected to the motor cylinder 98. The tube 84 extends through and is slidably supported by a suitable bearing assembly 102 which is connected to the support plate 96.

Upon operation of the motor 16 to move the bucket 14 from the dump orientation to the dig orientation, the motor 16 is operated from a fully extended condition to the partially retracted condition of FIG. 4. As the motor 16 is retracted, a first or dig position magnet 108 (FIG. 5) is moved from a position to the left (as viewed in FIGS. 4 and 5) of the detector 64 to a posi tion immediately adjacent to the detector (FIG. 5). When the permanent magnet 108 is immediately adjacent to the detector 64, a magnetic field I12 (FIG. 7) emanating from the permanent magnet 108 causes a known reed type of proximity switch in the detector 64 to be actuated to a closed condition.

Upon closing of the reed switch in the detector 64, a circuit is completed to energize the solenoid 68 (FIG. 3). As was previously mentioned, energization of the solenoid 68 moves the valve 70 to the actuated position illustrated in FIG. 3 to effect operation of the piston motor assembly 74 to release the detent assembly 46. Upon operation of the detent assembly 46 to the released condition. the control handle 36 and motor controller valve 38 are moved to neutral by the return spring 48. When this occurs, the bucket 14 is hydraulically locked in the dig orientation by the motor 16.

As the bucket positioning motor 16 is retracted to move the bucket 14 to the dig orientation, a leading end portion or pole 116 of the magnet 108 (see FIG. 5) approaches the detector 64. If the magnetic field 112 emanating from the permanent magnet 108 has its normal or undisturbed pattern, lines of flux, illustrated schematically at 120 in FIG. 7, would be rather dense adjacent to the leading end 116 of the permanent magnet 108. Thus, the undisturbed magnetic field at the leading end 116 of the magnet 108 would have the same density as a trailing end pole 124 of the magnet. The relatively dense flux field at the leading end of the magnet could cause premature activation of the detector 64. In addition, the dense flux fields adjacent to the opposite ends 116 and 124 of the magnet 108 could cause the reed switch in the detector 64 to be double pulsed or actuated as the magnet 108 moves past the detector 64.

To prevent premature activation of the detector 64 and/or double pulsing of the detector 64, a pole shading member 130 is provided to diffuse or disperse the portion of the magnetic field 112 associated with the leading end 116 of the magnet 108. The diffused portion of the magnetic field 112 is of insufficient strength or density to cause premature activation of the detector 64 as the leading end 116 of the magnet 108 approaches-the detector. However, once the trailing end or pole 124 of the permanent magnet 108 is adjusted to the detector 64, the relatively dense portion of the magnetic field 112 emanating from the trailing end of the magnet causes the reed switch in the detector 64 to be closed.

The lines of flux forming the magnetic field 112 have been illustrated schematically in FIG. 7. It should be noted that the flux lines 120 are relatively dense or closely spaced adjacent to the trailing end 124 of the magnet 108. However, the cylindrical pole shading member 130 is formed of a magnetizable ferrous material and therefore provides an extension of the leading pole or end 116 of the cylindrical magnet 108. This results in the flux lines 120 being separated so that the magnetic field 112 is relatively open or dispersed adjacent to the leading end 116 of the magnet 108. This relatively open portion of the magnetic field 112 is of insufficient density or strength to activate the detector 64. It should be understood that the schematic representation of the magnetic field 112 in FIG. 7 is for purposes of illustration only and the actual magnetic field associated with the permanent magnet 108 and pole Shading member 130 may have a configuration which is somewhat different than the illustrated configuration.

When the bucket 14 is to be moved from the dig orientation shown in solid lines in FIG. 1 to the carry orientation shown in dashed lines in FIG. 1, the motor 16 is retracted from the position shown in FIG. 4. When this occurs, the piston rod 88 and tube 84 are moved toward the right (as viewed in FIGS. 4 and 5). This moves the dig position magnet 108 away from the de tector 64 so that the solenoid 68 is deenergized and the valve is moved to a position blocking a flow of fluid from the pump 40 to the piston and cylinder assembly 74 (see FIG. 3). When this occurs, the roller 52 on the detent assembly 56 engages the notch 54 to hold the actuator lever 36 and motor control valve 38 in an actuated condition porting high pressure fluid to the rod end of the motor 16 through the conduit 32.

As the motor 16 is retracted. the bucket 14 moves toward the carry orientation shown in dash lines in FIG. 1 and a carry position magnet 136 approaches the detector 64. When the bucket 14 reaches the carry orientation, the magnetic field emanating from the cylindrical permanent magnet 136 is effective to activate the detector 64. Activation of the detector 64 results in an output signal over the lead 66 (FIG. 3) to energize the solenoid 68. Energizing the solenoid 68 actuates the valve 70 to cause the piston and cylinder assembly 74 to be operated to release the detent assembly 46. When the detent assembly 46 has been released, the control lever 36 and motor control valve 38 are returned to their neutral positions under the influence of the biasing spring 48. Since the motor control valve 48 blocks fluid flow to and from the motor 16, the bucket 14 is held in the upright carry orientation shown in dashed lines in FIG. 1.

Once the bucket 14 has been moved to the carry orientation, the bucket elevating motor 22 is extended to move the boom 12 from the lowered position of FIG. 1 to the raised position of FIG. 2. The vehicle 10 is then driven to an unloading or dump location. At the unloading location, the control lever 36 is pivoted in a clockwise direction from the neutral position shown in FIG. 3. This actuates the motor control valve 38 to port fluid under pressure through the conduit 30 to the head end of the motor 16. As the motor 16 is extended, the bucket 14 is moved from the carry orientation to the dump orientation (shown in dashed lines in FIG. 2). It should be noted that as the motor 16 is extended, the magnet 108 is effective to activate the detector 64 when the bucket reaches the dig orientation. However, it is contemplated that the operator will hold the control lever 36 in an actuated condition so that even though the detent assembly 46 is released, the bucket 14 continues to move to the dump orientation.

Once the load has been emptied from the bucket 14, the vehicle 10 is driven back to the loading or digging location, the boom 12 is lowered and the bucket 14 is returned to the dig orientation. To initiate movement of the bucket 14 from the dump orientation to the dig orientation, the operator merely moves the control lever 36 in a counterclockwise direction from the neutral position shown in FIG. 3. As the lever is moved, the detent roller 52 is pressed into the notch 54 to hold the motor control valve 38 in an actuated condition porting high pressure fluid to the conduit 32 and the rod end of the motor 16. As the motor 16 is retracted, the cylindrical pole shading member and leading end 116 of the permanent magnet 106 approach the detector 64. When the magnet 108 is moved to the position shown in FIG. 5 and the bucket 14 is in the dig orientation shown in solid lines in FIG. 1, the detector 64 is activated under the influence of the magnetic field emanating from the magnet 108 to effect operation of the solenoid 68 and a releasing of the detent assembly 46.

It is contemplated that under certain operating conditions it may be desirable to move the bucket 14 rearwardly, that is in a counterclockwise direction from the carry orientation shown in dashed lines in FIG. 1. Therefore, once the bucket has moved to the carry orientation and the permanent magnet 136 has effected activation of the detector 64 to release the detent assembly 46 in the manner previously explained, the operator may manually press the lever 36 in a counterclockwise direction from the neutral position shown in FIG. 3. Of course, this will actuate the motor control valve 38 to continue movement of the bucket 14 in a counterclockwise direction from the carry orientation until a mechanical limit stop is engaged and further motion stopped.

If desired, the actuator rod assembly 62 could be constructed in such a manner that the detector 64 would be rendered inactive upon initial movement of the permanent magnet 136 toward the right (as viewed in FIG. during retraction of the motor 16. This would enable the detent assembly 46 to maintain the motor control valve in an actuated condition porting fluid under pressure to the rod end of the motor 16. However, the cylindrical permanent magnet 136 is provided with a cylindrical pole shading member 140 which abuts the trailing or outer pole 142 of the magnet. Since the cylindrical pole shading member 140 is made of a magnetizable ferrous material. it is effective to diffuse the field emanating from the permanent magnet 136 in much the same manner as is shown in FIG, 6 for the magnet 108. Although the diffused field of the magnet 136 is not of sufficient density to effect operation of the reed switch in the detector 64. the diffused magnetic field is of sufficient strength or density to maintain the switch in a closed condition.

During retraction of the motor 16 to move the bucket 14 rearwardly from the carry orientation, the detector 64 is maintained in an activated condition providing an output signal to energize the solenoid 68 and maintain the detent assembly 46 in a disengaged condition. Therefore during movement of the bucket 14 rearwardly from the carry orientation, the control lever 36 must be held in an actuated condition to maintain the motor control valve 38 in an operated condition. Upon releasing the control lever, the biasing spring 48 operates the motor control valve 38 to a closed condition blocking fluid flow to and from the motor 16.

The cylindrical permanent magnets 108 and 136 and cylindrical pole shading members 130 and 140 are advantageously disposed in a coaxial relationship in an elongated cylindrical chamber 144 (FIG. 5) within the tube 84. A plurality of cylindrical spacer members 146 are utilized to hold the magnets 108 and 136 in a desired location within the elongated tube 84. The spacer members 146 are made ofa nonmagnetizable material, such as wood, and do not effect the field emanating from the magnets 108 and 136.

The axial positions of the magnets 108 and 136 in the tube can be adjusted to enable the positions of the bucket 14 in the dig and carry orientations to be adjusted. Thus, an externally threaded plug member 150 engages internal threads 152 formed on the inside of the tube 84. Similarly, an internally threaded plug member 156 engages internal threads 158 at the opposite end of the tube 84. When the position of the magnet 136 is to be adjusted, it is merely necessary to turn the threaded plug 156 relative to the tube 84. The interaction between the threads on the plug and tube cause the plug to be moved axially. A biasing spring 162 is provided between the magnets 136 and 108. Therefore, upon axially outward movement of the threaded plug member 156, the biasing spring 162 moves the magnet 136 axially outwardly that is toward the left as viewed in FIG. 5). Upon axially inward movement of the plug 156, the spring 162 is compressed and the magnet 136 moves inwardly (that is toward the right as viewed in FIG. 5).

Similarly, upon axially inward movement of the threaded plug 150, the magnet 108 is moved inwardly and the spring 162 is compressed. Upon rotation of the threaded plug in the opposite direction, the magnet 108 is moved outwardly under the influence of the spring 162.

A pointer 166 is connected with one end of the actuator rod assembly 62 and cooperates with a reference marker 168 (see FIGS. 4 and 5) to provide a visual indication of the position of the bucket 14. Thus, when the bucket 14 is in the dig orientation the pointer 166 is aligned with the reference member 168. As the bucket is moved from the dig orientation to the carry orientation the motor 16 is retracted and the pointer 166 moves to the right (as viewed in FIG. 4) of the reference member 168. When the bucket 14 is in the dump orientation the motor 16 is fully extended and the pointer 166 is to the left (as viewed in FIG. 4) of the reference member 168.

The pointer 166 is connected with the threaded plug 150. Therefore, when the threaded plug 150 is moved axially relatively to the tube 84 to adjust the position of the magnet 108 and the dig orientation of the bucket 14, the position of the pointer 166 will also be adjusted relative to the motor cylinder 98 and tube 84. Although only a single reference member 168 cooperates with the pointer 166 to provide a clear indication when the bucket 14 is in the dig orientation, it is contemplated that similar reference members could be mounted on the motor cylinder 98 to provide a visual indication of when the bucket 14 is in the carry and dump orientations.

When the boom 12 is to be moved from the lowered position of FIG. 1 to the raised position of FIG. 2, an operator lever 174 (FIG. 8) is moved clockwise from the illustrated position to actuate a motor control valve 176 to effect operation of the bucket elevating motor 22 from the retracted condition of FIG. 1 to the extended condition of FIG. 2. The motor control valve 176 is of the same construction as the motor control valve 38 of FIG. 3 and cooperates with a detent assembly 108 in the same manner as in which the motor control valve 38 cooperates with the detent assembly 46.

In accordance with a feature of the present invention, a detector 182 (FIG. 8) mounted on a frame member 184 is activated by a magnet 186 mounted on the boom 12 when the bucket 14 is moved to the raised position of FIG. 2. The detector 182 is connected with a solenoid actuator valve 190 which is energizable to effect operation of a piston and cylinder assembly 192 to release the detent assembly in the manner previously explained in connection with the detent assembly 46 and piston and cylinder assembly 74. Thus, as the boom 12 is raised, a support arm 194 is moved in a counterclockwise direction (as viewed in FIG. 8) about a connection 196. This movement of the support arm 194 moves the permanent magnet 186 adjacent to the detector 182. The magnetic field emanating from the permanent magnet 186 actuates a reed switch in the detector 182 to complete a circuit and effect energization of the solenoid 190. Of course. energizing the solenoid 190 results in the detent assembly 180 being released so that operation of the bucket elevating motor 22 is interrupted with the boom 12 in the raised position of FIG. 2.

To enable the raised position of the boom 12 to be adjusted, the permanent magnet 186 is connected with an arcuate support member 202 which is fixedly con nected to the support arm 194. The support member 202 defines an arcuate slot 206 having a center coincident with the center of the connection 196 about which the support arm 194 is rotated. Therefore, an adjustable connector 208 which extends through the slot 206 can be released and the magnet 186 moved along the slot 206 without changing the position of the magnet relative to the detector when the boom 12 is in the raised position. If the center of the arcuate slot 206 was not coincidental with the center about which the arm 194 moves, the position of the magnet 186 relative to the detector 182 would vary with variations in the position of the magnet along the slot.

When the boom 12 is to be lowered, the actuator lever 174 is moved in a counterclockwise direction from the position shown in FIG. 8. This operates the motor controller valve 176 to port fluid under pressure of the rod end of the bucket elevating motor 22. As the bucket elevating motor 22 is retracted, the boom 12 is lowered.

In view of the foregoing description, it can be seen that the material handling vehicle includes a bucket 14 which is movable between dig, carry, and dump orientations by a bucket positioning motor 16. When the bucket has been moved from the dump orientation to the dig orloading orientation, the magnet 108 activates the detector 64 to provide an output signal which energizes a solenoid 68 to interrupt operation of the bucket positioning motor 16. To prevent premature actuation of the detector 64 as the bucket moves toward the dig position, a pole shading member 130 of a magnetizable material is disposed adjacent to the leading end 116 of the magnet 108. The pole shading member 130 diffuses or disperses the portion of the magnetic field as associated with the leading end of the magnet 108 so that the detector 64 is not actuated until the trailing end 120 of the magnet 108 is closely adjacent to the detector 64. A visual indication of the fact that the bucket 14 is in the dig orientation is provided by the pointer 166.

After the bucket has been loaded in a known manner, the bucket positioning motor 16 is operated to move the bucket 14 to the upright carry orientation. When the bucket 14 reaches the carry orientation, a second magnet 136 activates the detector 64 to provide an output signal to interrupt operation of the bucket positioning motor 16. The two cylindrical permanent magnets 108 and 136 are advantageously disposed within a tubular member 84 formed of a nonmagnetizable material. In order to provide a precise adjustment of the magnets 108 and 136 relative to the tubular member 84 and the detector 64, the threaded end plug 150 can be adjusted axially to vary the position of the magnet 108 and the threaded end plug 156 can be adjusted axially to vary the position of the magnet 136.

Once the bucket 14 has been loaded and moved to the carry orientation, the bucket is moved from the lowered position of FIG. 1 to the raised position of FIG. 2 by extending the bucket elevating motor 22. When the bucket 14 has been moved to the raised position, the magnet 186 (FlG.8) activates the detector 182. Activation of the detector 182 provides an output signal to effect releasing of the detent assembly and movement of the motor control valve 176 to the neutral or unactuated condition blocking fluid flow to and from the bucket elevating motor 22.

Although the actuator rod assembly 64 has been disclosed herein in association with a motor 16 for positioning a bucket 14, it is contemplated that the actuator rod assembly could be used in many different environments. It should also be understood that the actuator rod assembly 64 could have a configuration other than the linear configuration disclosed herein. It is also contemplated that under certain circumstances the actuator rod assembly 64 may be spaced apart from the motor with which it is associated.

Having described specific preferred embodiments of the invention, the following is claimed:

1. A material handling apparatus comprising bucket means for carrying materials, motor means for moving said bucket means between first and second positions, a magnet having first and second magnetic poles, detector means actuable under the influence of the magnetic field emanating from said magnet to provide an output signal upon movement of said bucket means to said second position, means connected to said motor means for effecting relative movements between said magnet and detector means to reduce the distance between said magnet and detector means during movement of said bucket means from said first position to said second position, said magnet being disposed in such an orientation relative to said detector means that I said first magnetic pole is closer to said detector means than said second magnetic pole during movement of said bucket means toward said second position, and pole shading means comprising a member made of a magnetizable material disposed adjacent to said first magnetic pole for diffusing the portion of the magnetic field associated with said first magnetic to a greater extent than the portion of the magnetic field associated with said second magnetic pole to insure actuation of said detector means only when said second magnetic pole is adjacent said detector means thereby preventing premature actuation of said detector means by said first magnetic pole during movement of said bucket means toward said second position.

2. An apparatus as set forth in claim 1 wherein said means for effecting relative movement between said magnet and detector means includes an elongated tubular support member formed of a nonmagnetic material and connected with said motor means for movement relative to said detector means upon operation of said motor means, said magnet being disposed within said tubular support member and being movable therewith relative to said detector means upon operation of said motor means.

3. An apparatus as set forth in claim 2 wherein said pole shading means includes a metallic member made of a magnetizable material disposed within said tubular support member in engagement with said magnet.

4. An apparatus as set forth in claim 3 wherein said magnet and metallic member are disposed in a coaxial relationship in said tubular support member, said apparatus further including adjustment means for adjusting the position of said magnet and metallic member rela tive to said tubular support member.

5. An apparatus as set forth in claim 2 further including pointer means connected with said tubular support member for providing a visual indication of the position of said bucket means.

6. An apparatus as set forth in claim 1 wherein said bucket means is movable from said first position to a third position. said apparatus further including a second magnet, said means for effecting relative movement being operable to move said second magnet and detector means into a spatial relationship such that the magnetic field emanating from said second magnet is effective to actuate said detector means to provide an output signal when said bucket means is in said third position.

7. A material handling apparatus comprising bucket means movable in one direction from a loading orientation to a carry orientation and in another direction from the loading orientation to a dump orientation, linkage means for moving said bucket means between said loading, carry and dump orientations, motor means for effecting operation of said linkage means to move said bucket means, said motor means being operable in a first direction to effect movement of said bucket means from said dump orientation through said loading orientation to said carry orientation, said motor means being operable in a second direction to effect movement of said bucket means from said carry orientation through said loading orientation to said dump orientation, valve means operable from a neutral condition to a first actuated condition to effect operation of said motor means in said first direction and from said neutral condition to a second actuated condition to effect operation of said motor means in said second direction. first and second spaced apart magnets operatively connected with said motor means. said first magnet having first and second magnetic poles and being movable from a first inactive position to a first reference position upon operation of said motor means in said first direction to effect movement of said bucket means from said dump orientation to said loading orientation and being oriented with said first pole disposed closer to said first reference position than said second pole during movement of said bucket means from said dump orientation toward said loading orientation, said second magnet being movable from a second inactive position to a second reference position upon operation of said motor means in said first direction of effect movement of said bucket means from said loading orientation to said carry orientation, pole shading means comprising a member made of a magnetizable material disposed adjacent to the first magnetic pole of said first magnet to diffuse the portion of the magnetic field associated with said first pole to a greater extend than the portion of the magnetic field associated with said second pole, detector means for providing a first output signal when said first magnet reaches said first reference position as said motor means is operated in said first direction to move said bucket means from said dump orientation to said loading orientation, saidpole shading means being operable to insure that said first output signal is effected only when the second pole of said first magnet reaches said first reference position, actuator means for effecting operation of said valve means from said first actuated condition to said neutral condition in response to said first output signal when said second magnet reaches said second reference position as said motor means is operated in said first direction to move said bucket means from said loading orientation to said carry orientation, said actuator means being operable to effect operation of said valve means from said first actuated condition to said neutral condition in response to said second output signal.

8. An apparatus as set forth in claim 7 wherein said second magnet has first and second magnetic poles with said second magnetic pole being closer to said second reference position during movement of said bucket means from said loading orientation to said carry orientation, pole shading means disposed adjacent to said first magnetic pole to diffuse the portion of the magnetic field associated with said first pole to a greater extend than the portion of the magnetic field associated with said second pole.

9. An apparatus as set forth in claim 8 wherein said detector means is operable from a first condition to a second condition to provide the second output signal under the influence of the relatively dense magnetic field associated with the second pole of said second magnet, said diffused portion of the magnetic field associated with the first pole of said second magnet being of sufficient strength to maintain said detection means in said second condition during operation of said motor means to move said bucket means past said carry orientation.

10. An apparatus as set forth in claim 7 further including detent means operable from an engaged condition holding said valve means against operation from one of said actuated conditions to said neutral condition to a disengaged condition, said actuator means including means for effecting operation of said detent means to the disengaged condition in response to either of said first and second output signals and means for effecting operation of said valve means to the neutral condition upon operation of said detent means to the disengaged condition.

11. An apparatus as set forth in claim 10 wherein said second magnet has first and second magnetic poles, pole shading means disposed adjacent to said first magnetic pole to diffuse the portion of the magnetic field associated with said first pole to a greater extend than the portion of the magnetic field associated with said second pole, said detector means being operable from a first condition to provide the second output signal under the influence of the relatively dense magnetic field associated with the second pole of said second magnet, said diffused portion of the magnetic field associated with the first pole of said second magnet being of sufficient strength to maintain said detector means in said second condition to provide said second output signal and maintain said detent means in said disengaged condition during operation of said motor means to move said bucket means past said carry orientation.

12. An apparatus as set forth in claim 7 further including an elongated tubular support member formed of a nonmagnetic material and defining an elongated chamber, said first and second magnets being disposed in a coaxial relationship in said elongated chamber, first adjustment means operatively connected with said first magnet for adjusting the position of said first magnet relative to the longitudinal axis of said tubular support member, and second adjustment means operatively connected with said second magnet for adjusting the position of said second magnet relative to the longitudinal axis of said tubular support member.

nected with said support member and movable from a first position to a second position as said support member moves from said lowered position to said raised position during operation of said second motor means, second detector means for providing a third output signal in response to movement of said third magnet to said second position to thereby indicate that said support member has moved to said raised position. 

1. A material handling apparatus comprising bucket means for carrying materials, motor means for moving said bucket means between first and second positions, a magnet having first and second magnetic poles, detector means actuable under the influence of the magnetic field emanating from said magnet to provide an output signal upon movement of said bucket means to said second position, means connected to said motor means for effecting relative movements between said magnet and detector means to reduce the distance between said magnet and detector means during movement of said bucket means from said first position to said second position, said magnet being disposed in such an orientation relative to said detector means that said first magnetic pole is closer to said detector means than said second magnetic pole during movement of said bucket means toward said second position, and pole shading means comprising a member made of a magnetizable material disposed adjacent to said first magnetic pole for diffusing the portion of the magnetic field associated with said first magnetic to a greater extent than the portion of the magnetic field associated with said second magnetic pole to insure actuation of said detector means only when said second magnetic pole is adjacent said detector means thereby preventing premature actuation of said detector means by said first magnetic pole during movement of said bucket means toward said second position.
 1. A material handling apparatus comprising bucket means for carrying materials, motor means for moving said bucket means between first and second positions, a magnet having first and second magnetic poles, detector means actuable under the influence of the magnetic field emanating from said magnet to provide an output signal upon movement of said bucket means to said second position, means connected to said motor means for effecting relative movements between said magnet and detector means to reduce the distance between said magnet and detector means during movement of said bucket means from said first position to said second position, said magnet being disposed in such an orientation relative to said detector means that said first magnetic pole is closer to said detector means than said second magnetic pole during movement of said bucket means toward said second position, and pole shading means comprising a member made of a magnetizable material disposed adjacent to said first magnetic pole for diffusing the portion of the magnetic field associated with said first magnetic to a greater extent than the portion of the magnetic field associated with said second magnetic pole to insure actuation of said detector means only when said second magnetic pole is adjacent said detector means thereby preventing premature actuation of said detector means by said first magnetic pole during movement of said bucket means toward said second position.
 2. An apparatus as set forth in claim 1 wherein said means for effecting relative movement between said magnet and detector means includes an elongated tubular support member formed of a nonmagnetic material and connected with said motor means for movement relative to said detector means upon operation of said motor means, said magnet being disposed within said tubular support member and being movable therewith relative to said detector means upon operation of said motor means.
 3. An apparatus as set forth in claim 2 wherein said pole shading means includes a metallic member made of a magnetizable material disposed within said tubular support member in engagement with said magnet.
 4. An apparatus as set forth in claim 3 Wherein said magnet and metallic member are disposed in a coaxial relationship in said tubular support member, said apparatus further including adjustment means for adjusting the position of said magnet and metallic member relative to said tubular support member.
 5. An apparatus as set forth in claim 2 further including pointer means connected with said tubular support member for providing a visual indication of the position of said bucket means.
 6. An apparatus as set forth in claim 1 wherein said bucket means is movable from said first position to a third position, said apparatus further including a second magnet, said means for effecting relative movement being operable to move said second magnet and detector means into a spatial relationship such that the magnetic field emanating from said second magnet is effective to actuate said detector means to provide an output signal when said bucket means is in said third position.
 7. A material handling apparatus comprising bucket means movable in one direction from a loading orientation to a carry orientation and in another direction from the loading orientation to a dump orientation, linkage means for moving said bucket means between said loading, carry and dump orientations, motor means for effecting operation of said linkage means to move said bucket means, said motor means being operable in a first direction to effect movement of said bucket means from said dump orientation through said loading orientation to said carry orientation, said motor means being operable in a second direction to effect movement of said bucket means from said carry orientation through said loading orientation to said dump orientation, valve means operable from a neutral condition to a first actuated condition to effect operation of said motor means in said first direction and from said neutral condition to a second actuated condition to effect operation of said motor means in said second direction, first and second spaced apart magnets operatively connected with said motor means, said first magnet having first and second magnetic poles and being movable from a first inactive position to a first reference position upon operation of said motor means in said first direction to effect movement of said bucket means from said dump orientation to said loading orientation and being oriented with said first pole disposed closer to said first reference position than said second pole during movement of said bucket means from said dump orientation toward said loading orientation, said second magnet being movable from a second inactive position to a second reference position upon operation of said motor means in said first direction of effect movement of said bucket means from said loading orientation to said carry orientation, pole shading means comprising a member made of a magnetizable material disposed adjacent to the first magnetic pole of said first magnet to diffuse the portion of the magnetic field associated with said first pole to a greater extend than the portion of the magnetic field associated with said second pole, detector means for providing a first output signal when said first magnet reaches said first reference position as said motor means is operated in said first direction to move said bucket means from said dump orientation to said loading orientation, said pole shading means being operable to insure that said first output signal is effected only when the second pole of said first magnet reaches said first reference position, actuator means for effecting operation of said valve means from said first actuated condition to said neutral condition in response to said first output signal when said second magnet reaches said second reference position as said motor means is operated in said first direction to move said bucket means from said loading orientation to said carry orientation, said actuator means being operable to effect operation of said valve means from said first actuated condition to said neutral condition in responSe to said second output signal.
 8. An apparatus as set forth in claim 7 wherein said second magnet has first and second magnetic poles with said second magnetic pole being closer to said second reference position during movement of said bucket means from said loading orientation to said carry orientation, pole shading means disposed adjacent to said first magnetic pole to diffuse the portion of the magnetic field associated with said first pole to a greater extend than the portion of the magnetic field associated with said second pole.
 9. An apparatus as set forth in claim 8 wherein said detector means is operable from a first condition to a second condition to provide the second output signal under the influence of the relatively dense magnetic field associated with the second pole of said second magnet, said diffused portion of the magnetic field associated with the first pole of said second magnet being of sufficient strength to maintain said detection means in said second condition during operation of said motor means to move said bucket means past said carry orientation.
 10. An apparatus as set forth in claim 7 further including detent means operable from an engaged condition holding said valve means against operation from one of said actuated conditions to said neutral condition to a disengaged condition, said actuator means including means for effecting operation of said detent means to the disengaged condition in response to either of said first and second output signals and means for effecting operation of said valve means to the neutral condition upon operation of said detent means to the disengaged condition.
 11. An apparatus as set forth in claim 10 wherein said second magnet has first and second magnetic poles, pole shading means disposed adjacent to said first magnetic pole to diffuse the portion of the magnetic field associated with said first pole to a greater extend than the portion of the magnetic field associated with said second pole, said detector means being operable from a first condition to provide the second output signal under the influence of the relatively dense magnetic field associated with the second pole of said second magnet, said diffused portion of the magnetic field associated with the first pole of said second magnet being of sufficient strength to maintain said detector means in said second condition to provide said second output signal and maintain said detent means in said disengaged condition during operation of said motor means to move said bucket means past said carry orientation.
 12. An apparatus as set forth in claim 7 further including an elongated tubular support member formed of a nonmagnetic material and defining an elongated chamber, said first and second magnets being disposed in a coaxial relationship in said elongated chamber, first adjustment means operatively connected with said first magnet for adjusting the position of said first magnet relative to the longitudinal axis of said tubular support member, and second adjustment means operatively connected with said second magnet for adjusting the position of said second magnet relative to the longitudinal axis of said tubular support member.
 13. An apparatus as set forth in claim 12 further including pointer means connected with said tubular support member for providing a visual indication of the orientation of said bucket means. 